JP3437088B2 - Homogenizer with beam rotation function and laser processing apparatus using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a homogenizer device for homogenizing the intensity in a beam cross section and a laser processing device using the homogenizer device.

[0002]

2. Description of the Related Art In a so-called TFT type liquid crystal display device, an active matrix is formed by using polycrystalline silicon obtained by at least partially crystallizing a hydrogenated amorphous silicon a-Si: H (hereinafter referred to as "amorphous silicon") thin film. Is known (for example, Japanese Examined Patent Publication No. 7-118443).

In order to carry out this polycrystallization at a low temperature, it is effective to irradiate an excimer laser beam which is a laser beam in the ultraviolet region. The excimer laser beam is homogenized by a beam homogenizer and the beam cross section is made linear. It is also known to scan a linear beam on an amorphous silicon thin film (see, for example, JP-A-10-104545) (for example, JP-A-9-293688).

The scanning of the linear beam is carried out in a direction orthogonal to the major axis direction of the linear beam. However, even if the scanning of the beam is controlled, the multi-beam scanning in the direction intersecting the major axis direction of the linear beam is performed. Since it is difficult to make the crystallization characteristics uniform in a strict sense, it is desirable to be able to change the major axis direction of the linear beam. However, in the case of an excimer laser, the size of the beam, the intensity distribution, and the discharge direction of the laser oscillator (the direction connecting the discharge electrodes facing each other (hereinafter also referred to as “discharge electrode direction”)) and the direction orthogonal to the discharge direction, If the divergence angle (divergence angle) is different and the homogenizer is simply rotated with respect to the low beam or raw beam from the laser oscillator, the characteristics of the linear beam itself will change. Therefore, in order to keep the characteristics unchanged even when rotated, it is necessary to rotate the homogenizer with respect to the excimer laser beam and also rotate the laser beam itself to be linearized by the homogenizer around the beam axis. is there.

Conventionally, the laser beam is rotated by a laser beam rotating device 100 as shown in FIG. 5 (a). In this laser beam rotation device 100, the laser beam passes through the optical path OP1 reflected by the mirrors MH1 and MH2, is then reflected by the mirror MH3 arranged at the position 103, and travels in the direction perpendicular to the plane of the drawing to the back. It is homogenized by a homogenizer (not shown) to be rectangular (shown by reference numeral 101 in the upper stage of (b) of FIG. 5) or after passing through the optical path OP2 reflected by the mirror MV1 and then reflected by the mirror MV2. And homogenized by a beam homogenizer (not shown; rotated by 90 ° compared to the case of beam incident through the optical path OP1) at the back of the plane of the figure and made into a rectangle (in the lower stage of (b) of FIG. 5). Code 10
(Indicated by 2) two kinds of rotating laser beams 101,
102 is obtained. In FIG. 5A, when the laser beam passes through the optical path OP2, the mirror MH1 is moved to the outside of the optical path OP2.

[0006]

However, in this laser beam rotating apparatus 100, as shown in FIG. 5B, two types of rectangles (or linear shapes) whose major axis is rotated by 90 degrees relative to each other. Only the beams 101 and 102 are obtained, and the long axis of the rectangular beam cannot be changed to an arbitrary direction. Further, in the laser beam rotation device 100, in order to switch the two beams 101 and 102, it is necessary to control the positions of a large number of optical elements (mirrors MH1, MH3, MV2 and a homogenizer element).

The present invention has been made in view of the above points, and an object of the present invention is to provide a homogenizer device with a beam rotation function capable of homogenizing a beam while rotating the beam at an arbitrary angle, and a laser processing device using the same. To provide.

[0008]

In order to achieve the above-mentioned object, the homogenizer device with a beam rotating function of the present invention, when the output beam is rotated by θ around an axis substantially parallel to the incident beam, 2 around the beam axis of the beam
A beam rotating optical element that rotates by θ, a beam homogenizer element on which an output beam from this beam rotating optical element is incident, and a beam axis of an incident beam that enters the homogenizer element when the beam rotating optical element is rotated by θ. And a homogenizer element rotating means for rotating 2θ around it.

In the homogenizer device with a beam rotation function of the present invention, "a beam rotation for rotating the output beam by 2θ about the beam axis of the beam when it is rotated by θ about an axis substantially parallel to the incident beam. Since an optical element is provided, the beam rotating optical element is rotated by θ about the axis with respect to the incident beam, thereby rotating the output beam from the element by 2θ about the beam axis of the output beam. obtain. Moreover, the homogenizer device of the present invention is provided with "a homogenizer element rotating means for rotating the beam homogenizer element by 2θ around the beam axis of the incident beam to the homogenizer element when the beam rotating optical element is rotated by θ". From the above, by rotating the homogenizer element by the homogenizer element rotating means twice the rotation angle θ of the beam rotating optical element (2θ),
It is possible to emit a homogenized beam that has been rotated by an arbitrary angle (2θ). Since the rotation angle (2θ) of the beam incident on the homogenizer element and the rotation angle (2θ) of the homogenizer element match, the characteristics of the low beam or the raw beam should depend on the direction in the beam cross section. In any case, it is possible to form a uniformized beam having the same characteristics without being affected by the characteristics.

Therefore, even if the intensity distribution, divergence angle, etc. of the beam are different between the discharge direction (discharge electrode direction) of the laser oscillator and the direction orthogonal thereto, such as the beam from an excimer laser oscillator, The same homogenized beam can be rotated and emitted in the same direction with respect to the cross section of the low beam from the laser oscillator.

Here, the rotation control of the homogenizer element by the homogenizer element rotating means may be performed in synchronization with the rotation control of the beam rotating optical element or separately. In the homogenizer device of the present invention, the rotational positions of the two optical elements, the beam rotation optical element and the homogenizer element, need only be controlled, so that control is also easy. Further, since the beam rotating optical element and the homogenizer element are positioned adjacent to each other, it is easy to control the rotation.

As long as the rotational position of the beam rotating optical element is controlled with the strictness usually required as an optical element, any supporting method or controlling method can be used around its axis.

In this specification, with respect to the beam rotating optical element, the "beam axis" of the outgoing beam is typically a line (beam central axis) along the traveling direction of the outgoing beam at the center of the beam cross section of the outgoing beam. ), If the output beam is in fact a collimated beam (parallel rays), as long as the output beam can be incident on the homogenizer element within the angular range in which it should actually be rotated, the output beam is It is only necessary that the line is along the traveling direction of the beam, and does not necessarily coincide with the beam center axis of the outgoing beam.

The beam rotating optical element is not particularly limited in its detailed structure as long as it can rotate the outgoing beam about the axis by a double angle (2θ) in response to the rotation of the element by the angle θ. The beam rotation optical element is configured to convert an incident beam that is incident parallel to the rotation axis of the element into a beam that is mirror-symmetrical with respect to one plane including the rotation axis and emit the beam.

In this case, the beam rotation optical element directs the incident beam to a virtual reflection plane fixed to the beam rotation optical element (the one plane including the rotation axis of the beam rotation optical element).
Is converted into a mirror-symmetrical beam and emitted, so that when the rotating optical element is rotated by θ with respect to the incident beam, the incident beam is rotated by −θ with respect to the virtual reflection plane of the rotating optical element. Therefore, the outgoing beam is rotated by θ with respect to the virtual mirror plane. Therefore, when the rotating optical element is rotated by θ with respect to the incident beam, the outgoing beam is rotated by 2θ with respect to the incident beam in the rotation direction of the rotating optical element. The rotation axis of the beam rotation optical element is
The axis of rotation of the outgoing beam and the axis of rotation of the homogenizer device also coincide (become in line). Therefore, it is easy to collectively perform the rotation control of the angle θ with respect to the beam rotation optical element and the rotation control of the angle 2θ with respect to the homogenizer element.

Here, with respect to the incident beam on the beam rotating optical element, "incident in parallel with the rotation axis of the beam rotating optical element" means "the incident beam is actually a parallel beam and its beam axis ( A line along the traveling direction of the beam, preferably the central axis of the beam, is parallel to the axis of rotation of the beam rotating optical element, provided that the beam does not have to be strictly parallel, for example, an excimer laser oscillator. The laser beam emitted from the laser may have a divergence angle (for example, on the order of 0.1 °) that the laser beam normally has.

The beam rotating optics preferably have "three reflective surfaces" or "have an entrance and exit refractive surface and a reflective surface located between these two refractive surfaces".

The reflecting surface and the refracting surface are preferably flat surfaces, but in some cases, may be curved surfaces having a certain degree of curvature in one direction or two directions. For example,
In the case of an excimer laser beam in which the incident beam has a certain divergence angle, the reflection surface or the incident refraction surface on which the beam is first incident among the three reflection surfaces has a degree of compensating the average beam divergence angle. It may have a curvature.

When the beam rotating optical element is composed of "three plane reflecting surfaces", the second reflecting surface is parallel to the virtual reflection surface, and the beam axis of the incident beam (rotation of the beam rotating optical element). The axis is parallel to the axis and is distant from the axis of rotation. On the other hand, the first and third reflecting surfaces are mirror images of each other with respect to the plane perpendicular to the rotation axis (equal angle to the second reflecting surface), and are spaced apart from the second reflecting surface. Located. Of course, as long as the three reflecting surfaces maintain the above relationship in the area where the beam hits and do not prevent the passage of the beam, the area (portion) where the beam does not hit may have any shape. Such three planar reflecting surfaces may be formed by coating or depositing a reflecting film on a rotatable support, fixing the reflector, or by polishing the surface of the support itself. May be. The support may be a single piece or an assembly.

If the beam-rotating optical element "has an entrance and exit refracting surface and a reflecting surface located between these two refracting surfaces with respect to the optical path of the beam", the beam-rotating optical element may, for example, be such that the reflecting surface is It consists of a dove prism that is arranged so as to be parallel to the virtual reflection surface.

The beam homogenizer element is a surface to be irradiated with a beam obtained by at least partially homogenizing a distribution of at least one characteristic (for example, intensity) in a beam cross section of an incident beam to the element in at least one direction. As long as it can be formed on the top, even if it is a type that uses reflection such as a kaleidoscope for uniformity,
Even the type that uses refraction such as fly eye,
It may be a combination of reflection and refraction, or any type. The beam shape emitted from the homogenizer element may be a linear shape, an elongated rectangular shape, an oval shape, or another shape such as a circle or a square.

In order to obtain a uniformized beam having an elongated rectangular shape or a linear cross-sectional shape as an outgoing beam, for example, as disclosed in Japanese Patent Laid-Open No. 10-104545,
It is possible to use a plate-shaped array in which cylindrical lenses are closely arranged in parallel along a generatrix and are arranged in a direction in which the generatrixes are orthogonal to each other and are separated from the condensing lens by different predetermined distances. When the beam is narrowed in the width direction by a homogenizer element so that the divergence angle tends to be large in the discharge direction in a discharge excitation excimer laser etc., the homogenizer element is arranged so as to narrow the beam in the direction perpendicular to the discharge direction. However, if desired, the homogenizer element may be arranged in a different direction (for example, a direction in which the beam is narrowed in the discharge direction or a direction in which the beam is narrowed obliquely to the discharge direction).

In order to achieve the above-mentioned object, the laser processing apparatus of the present invention has a laser oscillator which emits a beam having different characteristics depending on the directions in the beam cross section, and the above-mentioned laser beam which is emitted from the laser oscillator. It has such a homogenizer device and a homogenizer device, and is configured to irradiate the workpiece with the beam emitted from the homogenizer device.

Since the laser processing apparatus of the present invention is provided with the homogenizer apparatus as described above, the laser oscillator emits a beam having different characteristics depending on the direction in the beam cross section like the excimer laser oscillator. However, the beam can be rotated at any angle without changing the characteristics of the beam on the homogenized surface. Further, in the laser processing apparatus of the present invention, "the beam emitted from the homogenizer apparatus is configured to be homogenized on the workpiece."
Therefore, the surface of the work piece can be processed by scanning the surface of the work piece with homogenized light that has been rotated at an arbitrary angle with the same characteristics, in a desired direction. Therefore, for example, on the thin film, the direction (long-axis direction of the beam) in which the characteristics to be processed are desired to be as uniform as possible can be arbitrarily set.

The "laser oscillator which emits a beam having different characteristics depending on the direction in the beam cross section" is typically an excimer laser, but other gas lasers can be used as long as the similar problems can occur. However, it may be a solid-state laser such as a semiconductor laser. Also, while the "characteristic" in the beam cross section is typically intensity,
Depending on the case, other characteristics such as a spread angle may be used.

The laser processing apparatus of the present invention is typically
For example, it is composed of "a laser processing (annealing) device configured so that an emission beam from a homogenizer device is scanned on a thin film to anneal the thin film". However, the processing is not limited to annealing, but "surface modification Or “other optional processing”. Further, the work piece may be a bulk or a composite material instead of the thin film.

In the present specification, "annealing" means a treatment for bringing a substance into a thermally stable state,
For example, it is not limited to the treatment for bringing a substance in a polycrystalline state into a more thermally stable state, and includes changing a substance from an amorphous state such as amorphous silicon to a polycrystalline state. Here, the term "polycrystal" includes so-called microcrystals.

From the viewpoint of the method of the present invention,
The present invention states that " an axis is substantially parallel to the incident beam.
The output beam is rotated by an angle twice as large as the rotation angle.
A beam rotating optical element rotating about the beam axis of the beam is rotated about its axis by rotating the beam rotating optical element about an axis parallel to the beam axis of the laser beam incident on the element. Homogenized laser beam rotation comprising rotating and entering the homogenizer element, and rotating the homogenizer element about the beam axis of the laser beam entering the homogenizer element by twice the rotation angle of the beam rotating optical element. Method"
Further, by using this method, "a laser processing method for scanning the workpiece so that the beam from the homogenizer element is homogenized on the workpiece" is provided. .

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described based on a preferred embodiment shown in the accompanying drawings.

[0030]

1 (a) shows a laser processing apparatus 1 according to a preferred embodiment of the present invention. This laser processing device 1 is
It has a laser oscillator 2 and a homogenizer device 3 with a beam rotation function. Between the laser oscillator 2 and the homogenizer device 3, if necessary, a low beam B from the oscillator 2 may be provided.
A deflection mirror for changing the optical path of 0, an attenuator for adjusting the intensity of the beam B0, and a beam splitter for making it possible to monitor the intensity and distribution of the beam B0 on the upstream side and the downstream side of each deflection mirror. An optical system 4 including the above is provided, and a workpiece 6 having a surface 5 to be processed is disposed downstream of the homogenizer device 3. The workpiece 6
For example, in the case of a substrate provided with an amorphous silicon layer to be polycrystallized, the workpiece 6 is carried on a support which is capable of translation in a processing chamber provided with a laser beam transmission window and is translated. An optical system similar to the optical system 4 is provided between the homogenizer device 3 and the workpiece 6 as desired.

The laser oscillator 2 is, for example, like an excimer laser device, a discharge direction Y connecting discharge electrodes 7 and 8 (see FIG.
1 (b)) and the direction X orthogonal thereto, the size of the low beam or the raw beam B0, the intensity distribution,
It consists of laser oscillators with different beam divergence angles.

The homogenizer device 3 with a beam rotating function is
The beam rotation optical element 9 and the beam rotation optical element rotation control device 10a, the homogenizer 11 as a homogenizer element and the rotation control device 10b, and the control device 10c that synchronously controls the rotation control devices 10a and 10b.

In the following, it is assumed that the three-dimensional rectangular coordinate system X, Y, Z fixed to the floor (not shown) is adopted and the low beam B0 exiting the optical system 4 travels in the Z direction. In addition, the three-dimensional Cartesian coordinate system ξ, η, fixed to the beam rotation optical element 9
Take ζ as shown in FIG.

The beam rotating optical element 9 has three plane reflecting surfaces M1, M2 and M3, and is supported by a rotating body 15 which is rotatably supported around a rotation axis C1 which coincides with the beam center axis C0 of the low beam B0. Become. The rotation axis C1 on the ζ axis that coincides with the Z axis may be displaced from the central axis C0 as long as it is parallel to the central axis C0 of the beam. The first and third reflecting surfaces M1 and M3 are symmetric with respect to an imaginary plane S on the ξ-η plane perpendicular to the ζ axis (Z axis). The planes M1 and M3 intersect on the plane S along a straight line 16 parallel to the η axis. In addition,
The angle φ between each surface M1, M3 and the surface S is 45 ° <φ <
It is a desired angle satisfying 90 °. Second reflective surface M2
Is parallel to the η-ζ plane. Therefore, the reflecting surface M2 is perpendicular to the plane S and is parallel to the straight line 16 and the rotation axis C1.

In this rotating optical element 9, the laser low beam B0 made up of substantially parallel rays which travels in the Z (.zeta.) Direction and is incident on the reflecting surface M1 at the incident angle .phi. 2φ−90 °), reflected by the reflecting surface M2, then incident on the reflecting surface M3 at an incident angle φ, reflected by the reflecting surface M3, and rotated as an outgoing beam B1 in the Z (ζ) direction. Get out of the element. In this example, the beam central portion B incident on the reflecting surface M1 along the beam central axis C0
00 is a reflection surface M on a line M20 on the extension of the virtual plane S
The reflection surface M is so reflected as to enter the reflection surface M3 and exit from the reflection surface M3 as a beam B10 along the rotation axis C1.
The distance in the ξ direction between 1 (M3) and the reflecting surface M2 is adjusted. Of the low beam B0, the beam portion B0 incident on the reflecting surface M1 at the position most distant from the reflecting surface M2 in the ξ direction
After being reflected by the reflecting surfaces M1 and M2, 1 enters the reflecting surface M3 at the position closest to the reflecting surface M2, and is emitted in the Z (ζ) direction as a beam portion B11 closest to the reflecting surface M2. On the other hand, of the low beam B0, the beam portion B02 that is incident on the reflecting surface M1 at the position closest to the reflecting surface M2 is reflected by the reflecting surfaces M1, M2, and M3, and then the beam portion B12 farthest from the reflecting surface M2 in the ξ direction. Is emitted in the Z direction. That is, the beam B1 emitted from the rotating optical element 9 is inverted in the ξ direction with respect to the incident low beam B0. The positional relationship of the beam portion in the η direction is
The incident beam B0 and the outgoing beam B1 are the same. Therefore, the beam rotation optical element 9 is configured to detect the incident low beam B0.
Is a beam B1 having a cross-sectional distribution that is mirror-symmetrical with respect to a virtual mirror surface S1 (a surface including the rotation axis C1 of the beam rotating optical element 9 and parallel to the second reflecting surface M2) that coincides with the η-ζ surface.
It will be converted into and emitted.

Therefore, the rotating optical element 9 causes the incident beam B0
With respect to the Z (ζ) axis by θ, the incident beam B0 is − with respect to the virtual mirror plane S1 of the rotating optical element 9.
Since the output beam B1 is rotated by θ, the output beam B1 is rotated by θ in the rotation direction of the rotating optical element 9 with respect to the virtual mirror plane S1. When this is seen from the relationship between the incident beam B0 and the outgoing beam B1, the outgoing beam B1 is rotated by 2θ in the rotation direction of the rotary optical element 9 with respect to the incoming beam B0. That is, when the rotating optical element 9 is rotated by θ with respect to the incident beam B0, the output beam B1 is as follows when viewed from the coordinate system X, Y, Z fixed to the floor or the laser oscillator 2.
The incident beam B0 is a beam converted according to the matrix of the following (Formula 1).

[0037]

[Formula 1] ・ ・ ・ ・ ・ ・ ・ ・ ・ (Formula 1)

The beam homogenizer 11 is, for example, similar to the beam homogenizer disclosed in Japanese Patent Laid-Open No. 10-104545, four plate-shaped arrays 18a, 18 in which a large number of cylindrical lenses are closely arranged in parallel along a generatrix.
b, 18c and 18d are arranged so that the generatrixes of the cylindrical lenses are parallel or at right angles to each other and are separated from the condenser lens 19 by different predetermined distances. Below, the three-dimensional orthogonal coordinate system U, V, W fixed to the homogenizer 11 is considered. The W axis coincides with the rotation axis C2 of the homogenizer 11, and coincides with the Z axis and the ζ axis.

Cylindrical lens arrays 18a, 18
c is a combination of cylindrical lenses each having a generatrix extending in the V direction.
Each of b and 18d is formed by combining a cylindrical lens whose generatrix extends in the U direction.

In the arrays 18a and 18c, the beam portions incident on the respective cylindrical lenses constituting the array are U-shaped.
It works to collect light in the W plane. That is, the plurality of beam portions of the beam B1 are separately focused before the array 18c by the respective cylindrical lenses of the array 18a, then spread and enter the array 18c, and the divergence angle is reduced by the array 18c. A light collecting lens 19 positioned a little away from the object 6 finely collects the light in a same region 5a on the surface 5 to be processed of the work 6 and overlaps and homogenizes the region 5a. That is, the beam B1 is narrowed down by the arrays 18a and 18c and the condenser lens 19 while being overlapped in the U direction and being homogenized. on the other hand,
The arrays 18b and 18d work to condense the beam portion incident on each cylindrical lens forming the array within the VW plane. A plurality of beam portions of the beam B1 are focused by the respective cylindrical lenses of the array 18b and are incident on the array 18d which is adjacent to the array 18b, and the array 18d causes the lens 19 to focus on the lens 19 rather than the focus of the condenser lens 19.
In the same region of the work surface 5 of the work 6 in the form of a divergent or converging beam that is once focused and then spreads and enters the condenser lens 19 and is slightly condensed by the condenser lens 19. 5a is overlaid and homogenized. That is, the beam B1 is irradiated onto the surface 5 to be processed after being superposed and homogenized in the V direction by the arrays 18b and 18d and the condenser lens 19. As a result, the homogenizer 11 mixes the beam B1 in both the U direction and the V direction to homogenize the intensity of the beam B1 in the beam cross section (homogenize), while thinning in the U direction and long in the V direction. The surface B of the workpiece 6 is irradiated as a beam B2 having a rectangular or elongated rectangular cross section. Therefore, when the homogenizer 11 rotates about its rotation axis C2 (that is, the W axis) by an angle (for example, 2θ), the elongated region 5a in the V-axis direction also has the same angle (for example, 2) around the axis C2.
θ) It will rotate.

In the laser processing apparatus 1 of the preferred embodiment according to the present invention configured as described above, the rotary optical element 9 is initially arranged so that the ξ direction coincides with the X direction, and the U direction is the X direction. Homogenizer 11 to match
Next, the operation of the laser processing apparatus 1 will be described assuming that the positions are arranged.

When the X, ξ, and U axes are oriented in the same direction, the excimer laser oscillator 2 has (b1) and (c) in a substantially rectangular beam cross section as shown in (a1) of FIG.
It is assumed that the low beam B0 having the intensity (I) distribution in the Y and X directions as shown in 1) is emitted through the optical system 4.
Here, while the distribution (c1) of the intensity I in the direction X orthogonal to the discharge direction Y of the excimer laser oscillator 2 is the distribution (c1) of the intensity I of the pseudo Gaussian type, the intensity I in the discharge direction Y is shown. Distribution (b1) is assumed to have a larger spread (slightly top flat) than the X direction. Assuming that the low beam B0 has a symmetrical distribution with respect to the X axis, the beam cross section of the beam B1 obtained as a result of being inverted in the ξ direction by the rotating optical element 9, the intensity distribution in the Y direction that coincides with the η direction, and the ξ direction The intensity distribution in the X direction that coincides with is substantially the same as that of the beam B0, as shown in (a2), (b2) and (c2) of FIG. Therefore,
Homogenizer 11 having U-axis in a direction coinciding with X-axis
2A shows a beam B2 having an elongated cross section obtained by homogenizing and condensing the beam B1 in the X-axis (U-axis) direction and in the Y-axis direction that coincides with the V-axis.
3), the area 5a of the surface 5 to be processed is irradiated with the beam cross section, the Y (V) axis direction intensity distribution, and the U (X) axis direction intensity distribution as shown in (b3) and (c3).

In this case, as shown in FIG. 3A, the beam B2, like an amorphous silicon film, is placed on the support so as to be translationally movable in the XY plane in the processing chamber. The elongated surface 5a1 extending in the Y direction is irradiated to the surface 5 to be processed of the workpiece 6 through the laser beam transmission window of the processing champer. Therefore, for example, by translating a support supporting the workpiece 6 in the -X direction, the amorphous silicon film is polycrystallized along the band-shaped irradiation locus 20a, or the polycrystalline silicon is stabilized. Annealing may be performed.
In addition, here, the scanning directions X and Y on the surface 5 to be processed of the workpiece 6 are defined by the beam homogenizer 11 and the workpiece 6.
Should be read according to the optical system arranged between the and. That is, for example, as shown by an imaginary line M5 in FIG. 1, a deflection (turn) mirror inclined by 45 ° is arranged between the beam homogenizer 11 and the workpiece 6 to direct the beam B2 in the Y or -Y direction. If the surface B to be processed is irradiated with the beam B2 instead, it should be clear that the X and Y directions on the surface 5 to be processed should be read as the X and Z directions in a system fixed to the floor. .

Next, for example, when the beam rotation optical element 9 is rotated by θ around the rotation axis C1 along the ζ axis (Z axis) by the rotation control device 10a, the low beam B0 becomes
The beam is converted by the rotating optical element 9 according to the conversion matrix shown in the above (Formula 1), and emitted as the beam B1. The outgoing beam B1 has a beam cross section as shown in (d2) of FIG. 2 and is rotated 2θ with respect to the original state. In addition, when this beam B1 is viewed in the coordinate systems U and V rotated by θ with respect to the coordinate axes ξ and η fixed to the rotating optical element 9, ξ is read as U in (c2) and (b2) of FIG. It has an intensity distribution such that η is read as V.
The beam B1 rotated by an angle 2θ is incident on the homogenizer 11, but the homogenizer 11 is also rotated 2θ by the rotation control device 10b, so that the beam B1 and the homogenizer 1 are rotated.
Since the relative positional relationship with 1 does not change, it is the same as before rotation except that it rotates 2θ with respect to the original state.
The beam B2 having the beam cross section shown in (d3) is emitted from the homogenizer 11. This beam B2 is (b3), (c) when viewed in the coordinate systems U and V fixed to the homogenizer 11.
The beam having the intensity distribution shown in 3) is rotated by 2θ. Therefore, even if the characteristic of the outgoing low beam B0 in the beam cross section has a direction dependency as in the excimer laser oscillator 2, the uniformized beam B2 can be rotated without being affected by the direction dependency.

The beam B2 obtained here is, as shown in FIG. 3C, formed on the surface 5 to be processed of the amorphous silicon film 5 in the elongated region 5a2 extending in the direction inclined by 2θ with respect to the Y direction. Is irradiated. Therefore, for example, by performing translational movement of a support or the like carrying the workpiece 6 in the −X direction, the amorphous silicon is polycrystallized along the band-shaped irradiation locus 20b, or annealing for stabilizing the polycrystal silicon is performed. Can be done. in this case,
For example, on a silicon film, a direction (Y
The polycrystallizing property of the silicon film can be made substantially uniform along the direction (inclined by 2θ with respect to the direction).
Even if the annealing characteristics of adjacent scanning portions vary due to fluctuations in the intensity of 0 or the like, linear portions having the same characteristics are inclined with respect to the X and Y axis directions. It is possible to avoid unevenness in display along the axial direction.

Since the above-mentioned angle θ can take an arbitrary value, for example, by setting θ to 45 °, as shown in FIG. 3B, 90 ° with respect to the Y direction.
Of course, it is also possible to irradiate the region 5a3 extending in the direction of (° axis direction) (scanning is in the Y direction).

In the above operation, the axis X, the axis ξ
And it will be clear that it does not depend on how the relative rotational position of the axis U is taken. Therefore, on the premise that the laser processing apparatus 1 is configured such that the workpiece 6 is arranged at the optical path length such that the beam portions of the beam B2 emitted from the homogenizer 11 are overlapped and homogenized, What must be done in advance is to determine the direction (rotation around the beam axis) of the beam cross section to be incident on the homogenizer 11 in consideration of the direction dependence of the beam cross section of the low beam B0. Once the method of obtaining the beam cross section to be homogenized by the homogenizer 11 is determined, the initial rotation angle of the rotating optical element 9 and the initial rotation angle of the homogenizer 11 may be determined so as to satisfy this condition. After that, the rotation control operation of each of the rotation control devices 10a and 10b may be controlled by the control device 10c so as to rotate the homogenizer 11 at an angle that is twice the rotation angle of the rotating optical element 9 from the initial position.

When the dispersion of the laser beams B0, B1 and B2 is not a practical problem, the beam rotating optical element is replaced by the type 9 having three reflecting surfaces as shown in FIG. As shown in FIG. 4, a type 25 having an entrance refraction surface R1 and an exit refraction surface R2 and an intermediate reflection surface M4 may be used. In the Dove prism type beam rotating optical element 25, the reflecting surface M4 functions similarly to the reflecting surface M2 of FIG.
Functions similarly to the reflecting surfaces M1 and M3 of FIG. The size of the apex angle and the size of each surface of the dove prism 25 may be set so that the low beam B0 incident parallel to the rotation axis C1 is emitted parallel to the rotation axis C2 that coincides with the axis C1. It is preferable that the reflecting surface M4 has a shape such that total reflection occurs, but in some cases, a reflecting film may be formed on the surface M4. It will be apparent that the laser processing apparatus 30 having the beam rotation optical element 25 instead of the beam rotation optical element 9 can function in practically the same manner as the laser processing apparatus 1.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a laser processing apparatus of a preferred embodiment according to the present invention.

2 is an explanatory view of various characteristics of a beam in the apparatus of FIG.

3 is a schematic explanatory view of an example of laser processing using the apparatus of FIG.

FIG. 4 is an explanatory view of a modified example of the apparatus of FIG.

FIG. 5 is a schematic explanatory view of a conventional laser beam rotation device.

[Explanation of symbols]

1, 30 Laser processing device 2 Laser oscillator 3 Homogenizer device with beam rotation function 5 Workpiece 5a Work area 6 Work surface 7, 8 Discharge electrode 9, 25 Beam rotation optical elements 10a, 10b Rotation control device 11 Beam homogenizer ( Element 15 Rotating body 16 Intersection lines 18a, 18b, 18c, 18d Cylindrical lens array 19 Condensing lenses 20a, 20b Scanning locus B0 Laser low beams B00, B01, B02 Beam portion B1 Beams emitted from the beam rotating optical element B10, B11, B12 beam part B2 beam homogenized by homogenizer C0 beam center axis of low beam C1 axis of rotation of beam rotating optical element C2 axis of rotation of homogenizer I intensity M1, M2, M3, M4 reflecting surface R1, R2 refracting surface S, S1 reflection Symmetry planes U, V, W Three-dimensional straight Coordinate system (homogenizer) X, Y, Z three-dimensional orthogonal coordinate system (floor) ξ, η, ζ three-dimensional orthogonal coordinate system (beam rotating optical element) phi angle (incident angle) theta rotation angle

Continuation of the front page (56) References JP-A-10-291318 (JP, A) JP-A-7-47481 (JP, A) JP-A-5-102062 (JP, A) JP-A-8-286382 (JP , A) JP-A-6-327710 (JP, A) JP-A-5-217851 (JP, A) JP-A 1-152411 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G02B 27/09 G02B 26/00 H01L 21/268 G03F 7/20

Claims (8)

(57) [Claims] 1. A beam rotating optical element for rotating an output beam by 2θ about a beam axis of the beam when the θ beam is rotated about an axis substantially parallel to the incident beam, and the beam rotating optical element comprises: A beam rotation having a beam homogenizer element on which the output beam of is incident and a homogenizer element rotating means for rotating the homogenizer element by 2θ about the beam axis of the incident beam to the homogenizer element when the beam rotation optical element is rotated by θ. Homogenizer device with function. 2. A beam rotation optical element is configured to convert an incident beam incident parallel to the rotation axis of the element into a beam which is mirror-symmetrical with respect to a plane including the rotation axis and emits the beam. The homogenizer device according to claim 1. 3. The homogenizer device according to claim 2, wherein the beam rotating optical element has three reflecting surfaces. 4. The homogenizer device according to claim 2, wherein the beam rotating optical element has an entrance and exit refracting surface and a reflecting surface located between these two refracting surfaces. 5. A laser oscillator that emits a beam having different characteristics depending on the direction within the beam cross section, and a beam emitted from this laser oscillator is incident.
And a homogenizer device according to any one of the above items, wherein the beam emitted from the homogenizer device is homogenized on the workpiece. 6. The laser processing apparatus according to claim 5, wherein the laser oscillator is an excimer laser oscillator, and the emission beam from the homogenizer device is configured to scan the thin film to anneal the thin film. 7. An axis substantially parallel to the incident beam
The output beam is rotated by an angle twice the rotation angle around it.
Rotate the beam rotation optical element around the beam axis by rotating the beam rotation optical element around the axis parallel to the beam axis of the laser beam incident on the element. A method of rotating a laser beam comprising causing the beam homogenizer element to enter the beam homogenizer element and rotating the homogenizer element about the beam axis of the laser beam incident on the homogenizer element by an angle that is twice the rotation angle of the beam rotating optical element. 8. A laser processing method using the beam rotating method according to claim 7, wherein the beam from the homogenizer element is homogenized on the workpiece to scan the workpiece. Laser processing method.